Fuse



Patented Feb. 16, 1932 UNITED STATES FRANK C. LA MAB, F NEW YORK, N. Y.`

FUSE

Application led February 2, 1931.

This invention relates to electrical devices, particularly electrical devices for breakmg an electrical circuit, and more especially to electrical devices known as renewable cartridge fuses.

The principal object of this invenion 1s the production of a thermal fuse, of the renewable knife blade cartridge type, devoid of filling, which includes an insulating spacing bar connecting the knife blades at each end of the fuse, and means for preventing the knife blades from falling into the cartridge upon the destruction of the thermal element and the insulating spacing member.

Other objects and advantages will appear as the description of the particular physical embodiment, and modification thereof, selected to illustrate the invention progresses, and the novel features will be particularly pointed out in the appended claims.

In describing the invention in detail and the particular physical embodiment and modification thereof, selected to illustrate the invention, reference will be had to the accompanying drawings and the several views thereon, in which like characters of reference designate like parts throughout the several views, and in which:

Figure 1 is a longitudinal sectional view of a cartridge fuse embodying my improvements; Fig. 2 is a longitudinal sectional view of a fuse embodying my improvements on a plane at a right angle to the plane upon which Fig. 1 is taken; Fig. 3`is an end view of the fuse as shown by Figs. 1 and 2; Fig. 4

is a cross-sectional view on the plane indicated by the line IVe-IV of Fig. 2, viewed in the direction of the arrows at the ends of the line; Fig. 5 is a sectional view on the plane indicated by the line V-V of Fig. 2, viewed in the direction of the arrows at the ends of the line; Fig. 6 is a separated or exploded view of the parts positioned in the interior 4,5 of the cartridge; Fig. 7 is a view of a modi- Betial N0. 512,845.

fied form of end construction; Fig. 8 is a. view of another modified construction.

In the drawings, numeral 1 designates an elongated hollow shell forming the main body of a fuse. This body is made of any well known and appropriate material, preferably horn fibre.

At each end of the cartridge, a ferrule, as 2 and 3, is attached in any well known and appropriate manner as by rivets 5. Each ferrule is formed with an external thread as 6.

The unitary knife blade assembly includes insulating spacing bar 7 and knife blades, 8 and 9, one at each end of the bar, together with the thermal or fusible element 10.

An insulating spacing bar 7 is attached to the knife blades, as 8 and 9, by through bolts, as 11, which also, by means of nut 12 and washer 13, serve to maintain the thermal strip 10 in contact with the knife blades.

In order to position the knife blades and to close the end of the ferrules, as 2 and 3, slotted washers 14 and 15 are positioned on each knife blade, as 8 and 9. The Washer 14 is of a size such, as shown in Fig. 4, that it can be passed through the-bore of the ferrules, as 2 and 3, and is rigidly attached, in any appropriate manner, as by soldering, to the knife blade with which it is associated, and is so positioned with relation to the end of the spacing bar 7 that when the washer 15 is placed thereon there is a space 16 between the inside face of the Washer 15 and the end of the ferrule 2. Washer 15, when in place, generally has its inner face bearing directly against the outer face of the washer 14. The washer 15 has two depending lugs 17 and 18, best shown in Fig. 6, which fit into slots 19 and 2O in the end of the ferrule, as 2, and also has protuberances, as 21, 22, 23 and 24, best shown in Fig. 6, which rest upon the end face of a ferrule, as 2, so as to space washer 15 from the end of the ferrule,

Washer 15 also has a button 26 attached to it but spaced therefrom, and a groove 27 90 therein in which is positioned a bolt 28 formed with an elongated slot 29 in which the stem 30 of the button is positioned. This bolt 28 further has a cam face 31 formed and pol5 sitioned to cooperate with a cam face 32 of the cap 33. rlhis cap 33 is formed with an internal thread 34 fitting the external thread 6 of the ferrules as 2 and 3.

When the cap 33 is screwed down on to a 10 ferrule the cam face 32 contacts with the cam 31 of the bolt and forces the bolt along a diameter of the washer and the end thereof into and through slot or orifice 35 of a knife blade, as 8 and 9.

In Fig. 7 I have shown a modification in which the bolt and its associated parts are dispensed with at one of the knife blade terminals. In this modification the washers, 37, corresponding to both washers 14 and 15, are 2@ both attached rigidlyto a knife blade, as 8.

In assembling the fuse a cartridge, as 1, havingferrules, as 2 and 3, thereon, is selected. A spacing bar, as 7, having knife blade terminals, as 8 and 9, secured thereto and a thermal strip, as 10, secured in place with the washers, as 14, at each end thereof secured in place, is passed longitudinally through the cartridge 1. Washers, as 15 are placed, one at each end of the knife blades,

with washers 14. Caps, as 33, are then placed, one on each end of the cartridge, and screwed down into place on the ferrule. In moving into place, the cap moves the bolts, as 28, diametrically along the washer, as 15, and causes the bolt 28 to pass through the slot in the knife blade.

If the modification as shown in Fig. 7 is used at one end, or at one knife blade, then the operation is the same except that no bolt is present, on one end, to be moved into a slot of the knife blade.

rllhe members 17 and 18 of each of the washf ers 15 lit into the slots of each of the ferrules andprevent rotational movement of the blades, as 8 and 9, and align them. At the same time a passage for gases is formed,

which is through the spaces, as 36, surrounding the washer 14, then through the space 16 5o between the washer 15 and the ends of the ferrule, and then along 'the cooperating screw threads 6 and 34, where the gases reach atmosphere.

In Fig. 8 a washer, 38, is shown which vis comparable with washer 14, but washer 38 has projection 39 and 40 which project into slots 19 and 20 and take the place of projections l 17 and 18 of washer 15, so that when washer 38 is used washer 15 may bedevoid of protuberances 17 and 18.

It is readily seen that just so long as spacing bar 7 is in place, the knife blades 8 and 9 are kept properly spaced, and that when spacing bar 7 is destroyed, the terminals 8 and 9 are also well retained in place, because they and move down into position into contact weave@ cannot move downwardly by reason of the engagement of fixed washer 14 and washer 15, and they cannot move inwardly because bolt 28 prevents such inward movement.

If the fusible element 10 is destroyed it is readily apparent that the cap 33 may be plained the principle and mode of operation and construction theref, nevertheless, I desire to have it understood that the form selected is merely illustrative, but does not exhaust the possible physical embodiments of the idea of means underlying my invention. What I claim as new and desire to secure by Letters Patent of the United States, is: v 1. In a cartridge-fuse, in combination: a knife blade formed with an orifice; a hollow body surrounding the lmife blade; a washer formed with a slot in which the blade is positioned, said washer resting on the body, said washer supporting a slidable bolt formed with a cam face; a cap, adapted for engagement with the body, formed with a cam face for engagement with the cam face of the bolt whereby the engagement of the cap with the body bolts the knife blade to the washer.

2. In a cartridge fuse, in combination: an elongated hollow body; an insulating bridge within the body; knife blades, one attached to each end of the bridge and extending without the body, one of the knife blades being formed with a. slot; a washer formed with a slot embracing the slotted knife blade, Said washer resting on the body and supporting a slidable bolt formed with a cam' face; a cap, adapted for engagement with the body, ormed with a cam face for engagement with the cam face of the bolt whereby the engagement of the cap with the body bolts the knife blade to the washer; and means for attaching the other knife blade to the adjacent end of the body.

3. In a cartridge fuse, in combination: a knife blade formed with a washer rigid therewith and with an orifice adapted for the reception of a bolt; a hollow body surrounding a portion of the knife blade; a second washer formed with a slot in which the blade is positioned, said second washer bearing against the rst washer and resting on the body; a button formed with a stem, the said stem being attached to said second wash-l er with the button spaced from the washer;

a bolt formed with a camface and with aslot in which said stem is positioned; a cap formed with a cam face for coaction with the cam face of the bolt and adapted for engagement with the hollow body.

4. In a cartridge fuse, in combination: a

knife blade formed with an orifice; a hollow body surrounding the knife blade; a washer formed with a slot in which the blade is ositioned, said washer su porting a slida le bolt formed with a cam ace; means for positioning the washer with relation to the knife blade; a cap, adapted for engagement with the body, formed with a cam face for engagement with the cam face of the bolt whereby the engagement of the cap with the body bolts the knife blade to the washer.

' FRANK C. LA MAR.

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